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-   -   To Stir Plate or Not To Stir Plate? (http://www.homebrewtalk.com/f163/stir-plate-not-stir-plate-181668/)

balazs 06-09-2010 02:05 PM

To Stir Plate or Not To Stir Plate?
 
I've been making yeast starters for a while now using the conventional 1 gallon jug with an airlock and have been able to grow lots of slurry without a problem. Lately I have been looking into making a stirplate. I just can't help but wonder though, is this something that will really make a better and healthier starter or is it more or less another brew toy (eye candy). I am aware that the stirplate keeps the yeast in suspension but how much healther does is make the yeast?

Homercidal 06-09-2010 02:36 PM

I enjoyed making and using my stirplate. I honestly can't tell it it's making a real difference or not. If you aren't interested in it for the cool toys factor, then I'm guessing you can get good results by simply picking up the container and shaking or swirling for a few seconds each time you walk past it.

The stirplate basically just keep the yeast in suspension, allow it to contact more food than otherwise. Once you've shaken the wort up, you probably have as much O2 in solution as it can hold. There may be some further exchange of gas at the surface of the wort once the yeast start consuming the O2 already in the wort, but how much benefit a stirplate gives over occasional stirring is debatable.

Revvy 06-09-2010 02:39 PM

A recent Basic Brewing Radio, may help you decide.

Quote:

May 13, 2010 - Stir Plates and Triangle Tests
Home Brewer Sean Terrill joins us again to follow up on his yeast starter aeration experiment. Also, Sean shares the results of his pitching rate experiment, recruiting dozens of home brewers to help evaluate.

- Sean's Yeast Pitching Rate Results http://seanterrill.com/2010/05/09/yeast-pitching-rate-results/
- Sean's Stirplate Design http://seanterrill.com/2010/04/26/build-a-better-stirplate/

Click to listen- MP3

BadgerBrewer 06-09-2010 02:42 PM

I liked making my plate as well. Awesome when it was done and worked!

If you check out MrMalty (http://www.mrmalty.com/calc/calc.html) and the suggested pitch starter needed, you will note that when you select stir plate versus simple starter, that the size of the starter goes down considerably the higher gravity beer you are making. I would say that this means stir plates are more effective at making healthy and more dense yeast colonies.

Homercidal 06-09-2010 04:01 PM

The point is that a stirplate will definitely create more healthy yeast in less time than a simple starter. However, I think the term simple starter means just adding your vial to a stationary jar of wort.

I can't help but wonder but that the occasional stir is also going to be more effective than simply letting it sit there undisturbed.

So the simple answer is yes, a stirplate is much better than nothing, but stirring a few times a day is probably very helpful too, as an alternative.

I recommend building one. It's easy and fun. I made mine out of an old printer selector box and an old computer fan. I used hard drive magnets mounted on the fan, and an old mobile phone charger to power the fan. It's crude, but it works.

There must be many threads in internet land that show people's stirplates. Lots of cool ideas.

a10t2 06-09-2010 04:22 PM

Quote:

Originally Posted by Homercidal (Post 2102717)
I can't help but wonder but that the occasional stir is also going to be more effective than simply letting it sit there undisturbed.

Essentially what I found is that *frequent* shaking is almost as good as a stirplate, and that direct aeration is the best technique of all: Aeration and Yeast Starters

Overall it seems that agitation doesn't do much in and of itself (for a low-gravity wort, anyway). The benefit of shaking or a stirplate comes primarily from turning over wort at the surface and increasing oxygen uptake.

Quote:

Originally Posted by Homercidal (Post 2102717)
So the simple answer is yes, a stirplate is much better than nothing, but stirring a few times a day is probably very helpful too, as an alternative.

I think that's a pretty good summary.

Barazs: you say you're using an airlock, which means that there will be almost no oxygen available once the yeast have exhausted the O2 in the headspace. At that point reproduction will stop and you'll only have fermentation going on. Other techniques for growing more yeast won't be effective unless you remove the airlock.

Sean

EricCSU 06-09-2010 05:15 PM

Quote:

Originally Posted by a10t2 (Post 2102764)
Other techniques for growing more yeast won't be effective unless you remove the airlock.

Exactly. Use loosely wrapped foil on top :rockin:

Eric

balazs 06-09-2010 05:54 PM

Good stuff! Thanks for all the info and links. Definatly will be making a stir plate after reading more on what they do for the yeast.

riromero 06-09-2010 06:25 PM

Quote:

Originally Posted by Homercidal (Post 2102717)
...
I recommend building one. It's easy and fun. I made mine out of an old printer selector box and an old computer fan. I used hard drive magnets mounted on the fan, and an old mobile phone charger to power the fan. It's crude, but it works.

There must be many threads in internet land that show people's stirplates. Lots of cool ideas.

I'm with you, brother. Computer fan and some kind of 9V charger I found in the bottom of my drawer is all I used too. But I can only make stirplate starters about 2/3rds of the time because I keep losing the damn stirbar. Seems like the stirplate method makes way more yeast.

EricCSU 06-09-2010 06:31 PM

Quote:

Originally Posted by riromero (Post 2103060)
I'm with you, brother. Computer fan and some kind of 9V charger I found in the bottom of my drawer is all I used too. But I can only make stirplate starters about 2/3rds of the time because I keep losing the damn stirbar. Seems like the stirplate method makes way more yeast.

Tape a magnet to the outside of the flask after using the stir plate but before pitching.

Eric


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